I played about 20-30 minutes and I wanted to improve rope length to see the deapest point. I think there are nothing after barrels. Also I went to right side of ocean but there are no difference. I enjoyed while playing, it is nice designed. There should be new things in the ocean and different things in different areas I think. 
Hello Entasy! Thank you very much for playing the game. Plastic Planet is still in early access at the moment. I am still working on the game, and there will be a lot more content in the future. There will be new biomes and new stuff to catch. In the next update, there will also be a save option, where you will be able to save and load your progress.
Thanks for your feedback!